1. Field of the Invention
The present invention relates to a substrate processing method and a substrate processing apparatus cleaning the surface of a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display, a glass substrate for a photomask or a substrate for an optical disk.
2. Description of the Background Art
In steps of manufacturing a substrate, particulate foreign materials (hereinafter referred to as “particles”) and various metal contaminants adhere to the surface of the substrate. Therefore, the surface of the substrate must be cleaned in a proper stage. The substrate can be cleaned by a batch method of simultaneously dipping a large number of substrates in a cleaning solution and processing the same and a single-substrate type method of rotating substrates one by one and supplying a cleaning solution to the surfaces of the substrates for processing the same.
A single-substrate type substrate processing apparatus has many advantages in process performance such as uniformity of the processing, reduction of particles, prevention of transfer of metal contaminants from another substrate etc. as compared with a batch-type substrate processing apparatus. Therefore, the single-substrate type substrate processing apparatus has mainstreamed in recent years. In the single-substrate type substrate processing apparatus processing substrates one by one, however, the processing must be performed in a shorter time as compared with the batch-type substrate processing apparatus in consideration of productivity.
In order to reduce the processing time in the single-substrate type substrate processing apparatus, ozone water and dilute hydrofluoric acid are employed as cleaning solutions, for example, for removing particles and metal contaminants from the surface of a substrate through steps including processing of about 15 seconds with the ozone water and processing of about 20 seconds with the dilute hydrofluoric acid.
Also in this attempt, however, the particles and the metal contaminants are removed through the etching force of hydrofluoric acid, leasing to another problem that the quantity of etching on the surface of the substrate is disadvantageously increased (the etching thickness reaches 2.0 nm, for example).